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midi module or synthesizer connected to the TI-99/4A


Dexter

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I spent more time with the nano tonight and have given up on it for now. It locks up sporadically during resets, locks up when loading program image files, and just isn't working like it should. I am going to set up another TI system to rule out the console, even though the current console works perfectly with my PEB and its various peripheral cards. I may need to contact the seller for options, as I really want to use the device...

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My DB25 to 5-pin DIN midi cable is built just like Gazoo posted. I used a multimeter to confirm the connections.

 

There is only one ground connection on the DB9 PC serial port and a few searches seemed to indicate MIDI pins 4 and 5 are the important connections. So I'm not quite sure if the 2nd ground is needed with the nano. Here's what I could figure out so far... see what you think.

 

 

post-25764-0-45448700-1489350190_thumb.png

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That third connection was goofing me up as well. I feel better that you've done some research on it so I'm going to put together a cable. I'll report my findings. Thank you.

I made a cable this afternoon but didn't have any luck as Midi Master just locks up at random places and even fails to load MIDI files. Until I can sort out what is wrong with my nano, I can't tell what is at fault. I did reach out to the seller and am awaiting a reply.

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You probably know all of this, but the nanoPEB v1 is wired as DTE. This is quoted from the manual:

 

“The port connector is a modern DB9 in DTE (data terminal equipment configuration). The only handshake signals supported are DTR and CTS.”

 

I do not know whether I can imply from this that the DSR and RTS lines are supported. I am not sure why the nanoPEB v1 would not also have them available. You need those to associate with DTR and CTS, respectively, if you expect to hook two computers together with hardware handshaking. But, if they are not supported, I suppose this could be the problem.

 

The TI RS232 card, on the other hand, is wired as DCE. The problem with the description in Appendix B of the TI manual is that the RD and TD lines are mislabeled. The signal directions are correct but the mislabeling is confusing because the TD line for DCE is supposed to connect to the TD line of DTE. The same for the RD line connections. All of the other lines are correctly labeled for DCE. Contrary to what the manual states, computer RS232 interfaces are usually DTE. Why would you need a Carrier Detect as output for a computer?

 

...lee

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You probably know all of this, but the nanoPEB v1 is wired as DTE. This is quoted from the manual:

 

Are you thinking the cable needs to be modified, Lee?

 

I compared the MidiMaster transmit routine to that in TIMXT, and both are identical. That said, it does look like the Midi program is stuck in a loop, possibly testing for the transmit buffer to empty. I don't know if we can tie the two grounds together, or if one is required over the other, since the available online information is sketchy (I can't find anything definitive).

 

Well, no success. The Roland pma-5 locks up and when pulling the din it states serial error. Looks like we're still in the weeds.

I heard back from the nanopeb seller. More to come as we work together to determine if my nano is defective...

 

information isn't 100% clear to me.

Edited by InsaneMultitasker
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Are you thinking the cable needs to be modified, Lee?

 

Possibly. I was partly thinking out loud. At least, I did want to make clear that the nanoPEB is not wired as the TI RS232 card is wired and, also, to suggest that I am interested in discovering exactly what pins on the nanoPeB are really active. I cannot check mine for a couple of weeks. I eagerly await your results. :)

 

...lee

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Possibly. I was partly thinking out loud. At least, I did want to make clear that the nanoPEB is not wired as the TI RS232 card is wired and, also, to suggest that I am interested in discovering exactly what pins on the nanoPeB are really active. I cannot check mine for a couple of weeks. I eagerly await your results. :)

 

...lee

Makes sense to me :) I was exchanging a few notes with Shift838. Perhaps there is something that needs to be done differently with it versus the TI RS232, depending on how the circuitry/pins are connected internally? Fred's site shows the following connections though it isn't clear to me if the signals are HDX-specific or if they represent the active nano signals.

 

Serial cable (Ti99Hdx with nanoPEB option)

For connecting your nanoPEB serial interface to a COM port of a PC you can use a standard RS232-cross cable. The connected signals of the nanoPEB's serial port is as follows:

#1 - Not connected

#2 - RXD

#3 - TXD

#4 - Not connected

#5 - GND

#6 - Not connected

#7 - RTS

#8 - CTS

#9 - Not connected

CfHdx uses to CTS signal to detect if the Ti99Hdx program is running on the PC.

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I launched TIMXT from the nano, with the MIDI cable connected. If I start typing, the second character typed locks the system tight. I suspect that the transmit buffer is full at this point, and TIMXT is waiting (ever so patiently) for the 9902 to signal the buffer is empty, to allow for the next load. I'm not sure how to address this scenario with the nano hardware.

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Well, no success. The Roland pma-5 locks up and when pulling the din it states serial error. Looks like we're still in the weeds.

Tonight I played my first MIDI song with the nano using MidiMaster version 2.5Z. :)

 

Using a 9-to-25 standard cable and my 25-pin breakout box, I checked the signals. Seems CTS and RTS need to be tied together. Assuming Fred's pinouts are correct, this means you need to jumper the nano serial port pins 7 and 8. I need to locate my continuity tester so that I can verify the pinouts. (I held little jumper wires in the 5-pin DIN to do a play test).

 

The weeds are clearing...

 

EDIT: Confirmed. Pins 7 and 8 must be jumpered! The second ground connection is not required. Lastly, I had to reverse the wires for pins 3 and 5 between the nano and midi. Not sure if the below diagram is right or wrong. I will sort out whether it is a documentation or cabling mistake when I'm not so tired. :sleep:

 

post-25764-0-23422200-1489467115_thumb.png

Edited by InsaneMultitasker
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